Many millions of people throughout the world suffer from a variety of urologic dysfunctions. Urologic dysfunctions are generally understood to include indications such as urinary incontinence, fecal incontinence, micturition/retention, defecation/constipation, sexual dysfunctions, pelvic floor muscle activity, and pelvic pain.
As one example, thirteen million Americans suffer from various types of urinary incontinence. The most prevalent type of urinary incontinence (22% of the total) is called Stress Incontinence (SUI). SUI is characterized by the unintended emission of urine during everyday activities and events, such as laughing, coughing, sneezing, exercising, or lifting. These activities and events cause an increase in bladder pressure resulting in loss of urine due to inadequate contraction of the sphincter muscle around the outlet of the bladder.
Another prevalent type of urinary incontinence (18% of the total) is called Urinary Urge Incontinence (UUI). UUI is characterized by a strong desire to urinate, followed by involuntary contractions of the bladder. Because the bladder actually contracts, urine is released quickly, making it impossible for urge incontinence sufferers to predict when the problem will occur. UUI can be caused by infections, sphincter disorders, or nervous system disorders that affect the bladder.
Many people (47% of the total) encounter a combination of bladder control disorders.
Damage to the bladder, urethra, periurethral muscles and sphincters, nerves, and accessory organs can be experienced by women during childbirth or hysterectomy. This damage can lead to urinary incontinence. Prostate problems can lead to urinary incontinence in men. The number of people suffering from urinary incontinence is on the rise as the population ages.
Various treatment modalities for urinary incontinence have been developed. These modalities typically involve drugs, surgery, or both. Disposable pads can also used, not to treat the disorder, but to deal with its consequences.
Pharmocotherapy (with and without attendant behavioral therapy) appears to moderate the incidence of urinary incontinence episodes, but not eliminate them. Drug therapy alone can lead to a reduction of incontinence episodes after eight weeks by about 73%. When combined with behavioral therapy, the reduction after eight weeks is about 84% (Burgio et al, JAGS. 2000; 48:370-374). However, others have questioned the clinical significance of the results, noting that the differences in outcomes using anticholinergic drugs and placebo were small, apart from the increased rate of dry mouth in patients receiving active treatment (Herbison P, Hay-Smith J, Ellis J, Moore K, BMJ 2003; 326:841).
One present surgical modality involves the posterior installation by a percutaneous needle of electrodes through the muscles and ligaments over the S3 spinal foramen near the right or left sacral nerve roots (INTERSTIM® Treatment, Medtronic). The electrodes are connected to a remote neurostimulator pulse generator implanted in a subcutaneous pocket on the right hip to provide unilateral spinal nerve stimulation. This surgical procedure near the spine is complex and requires the skills of specialized medical personnel. Furthermore, in terms of outcomes, the modality has demonstrated limited effectiveness. For people suffering from UUI, less than 50% have remained dry following the surgical procedure. In terms of frequency of incontinence episodes, less than 67% of people undergoing the surgical procedure reduced the number of voids by greater than 50%, and less than 69% reduced the number of voids to normal levels (4 to 7 per day). This modality has also demonstrated limited reliability. Fifty-two percent (52%) of people undergoing this surgical procedure have experienced therapy-related adverse events, and of these 54% required hospitalization or surgery to resolve the issue. Many (33%) require surgical revisions.
It has been reported that 64% of people undergoing some form of treatment for urinary incontinence are not satisfied with their current treatment modality (National Association for Incontinence, 1988).
A recently proposed alternative surgical modality (Advanced Bionics Corporation) entails the implantation through a 12 gauge hypodermic needle of an integrated neurostimulator and bi-polar electrode 16 assembly (called the BION® System) through the perineum into tissue near the pudendal nerve on the left side adjacent the ischial spine. See, e.g., Mann et al, Published Patent Application US2002/0055761. The clinical effectiveness of this modality is not known.
Stimulation of a target nerve N, such as the dorsal nerve of the penis (DNP) afferents activates spinal circuitry that coordinates efferent activity in the cavernous nerve (CN), increasing filling via dilation of penile arteries, and efferent activity in the pudendal nerve (PN), preventing leakage via occlusion of penile veins, producing a sustained reflex erection (see FIG. 1).
As an additional example, Erectile Dysfunction (ED) is often a result of a combination of psychological and organic factors, but it is thought to be purely psychological in origin in less than 30% of the cases. Organic factors can include complications from neurologic diseases (stroke, multiple sclerosis, Alzheimer's disease, brain or spinal tumors), chronic renal failure, prostate cancer, diabetes, trauma, surgery, medications, and abnormal structure. However, most cases of ED are associated with vascular diseases. An erection cannot be sustained without sufficient blood flow into and entrapment within the erectile bodies of the penis, and vascular related ED can be due to a malfunction of either the arterial or the venous system.
Stimulation of a target nerve or nerves (generally the afferents), such as the cavernous nerves, pudendal nerves, perineal nerves, pelvic splanchnic nerves, dorsal genital nerves, hypogastric nerves, sacral nerve roots, and/or lumbar nerve roots, activates spinal circuitry that coordinates efferent activity in the cavernous nerve (CN), increasing filling via dilation of penile arteries, and efferent activity in the pudendal nerve (PN), preventing leakage via occlusion of penile veins, producing a sustained reflex erection.
There remains a need for systems and methods that can treat urologic dysfunctions, such as urinary incontinence, as a first line of treatment and for those who have not responded to conventional therapies, in a straightforward manner, without requiring drug therapy and complicated surgical procedures.